Projection display device

ABSTRACT

A projection display device includes a light source, a reflector, and a fixing portion. The device further includes a first air supply portion and a second air supply portion; a first air drawing portion which separates the cooling air from the first air supply portion into streams of the cooling air to guide one of the streams into an interior of the reflector in a first direction and to guide the other of the streams to the fixing portion in a second direction; and a second air drawing portion which separates the cooling air from the second air supply portion into streams of the cooling air to guide one of the streams into the interior of the reflector in a third direction and to guide the other of the streams to the fixing portion in a fourth direction.

This application claims priority under 35 U.S.C. Section 119 of aChinese Patent Application No. 200910190693.4 filed Sep. 29, 2009,entitled “PROJECTION DISPLAY DEVICE”. The disclosures of the aboveapplication are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection display device formodulating light from a light source, and enlarging and projecting themodulated light.

2. Disclosure of Related Art

A high luminance light source such as a metal halide lamp or a highpressure mercury lamp is used in a projection display device such as aliquid crystal projector. The light source is provided with a lamp (arctube) and a reflector, and is constructed to reflect light emitted fromthe lamp on the reflector and emit the reflection light in the forwarddirection. Since the light source is heated to a high temperature at thetime of light emission, it is necessary to cool the light source by acooling device.

In the above case, it is possible to use an arrangement, wherein acooling air is supplied to the interior of the reflector to cool thelamp. In this arrangement, plural cooling fans are disposed, and acooling air generated by each of the cooling fans is drawn into theinterior of the reflector in two different directions to preventlowering of the cooling performance of the light source, even if theprojector is installed in various postures.

A fixing portion (called as a reflector base) made of e.g. plaster isprovided at a rear end of the reflector to fixedly mount the lamp withrespect to the reflector. The lamp has a seal portion at an innerposition of the reflector base. When light from the lamp is emitted, theseal portion is heated to a high temperature by heat generation of thelamp. If the seal portion is exceedingly heated, the seal portion may bedeteriorated, with the result that the performance of the light sourcemay be deteriorated.

Since the seal portion is disposed at a position relatively away fromthe inner surface of the reflector, the seal portion may not besufficiently cooled, even if the cooling air is draw into the interiorof the reflector, as proposed in the aforementioned projector. In thiscase, it may be possible to enhance the cooling performance byincreasing the air volume of the cooling air. However, an enhancedcooling performance may excessively cool the lamp, which may obstruct anormal light emission.

SUMMARY OF THE INVENTION

A projection display device according to a main aspect of the inventionincludes a light source having a light emitting portion, a reflectorwhich reflects light emitted from the light emitting portion, and afixing portion which fixedly mounts the light emitting portion withrespect to the reflector. The projection display device further includesa first air supply portion and a second air supply portion which supplya cooling air; a first air drawing portion which separates the coolingair from the first air supply portion into streams of the cooling air toguide one of the streams of the cooling air into an interior of thereflector in a first direction and to guide the other of the streams ofthe cooling air to the fixing portion in a second direction; and asecond air drawing portion which separates the cooling air from thesecond air supply portion into streams of the cooling air to guide oneof the streams of the cooling air into the interior of the reflector ina third direction and to guide the other of the streams of the coolingair to the fixing portion in a fourth direction.

In the projection display device according to the main aspect of theinvention, the streams of the cooling air separated by the first airdrawing portion and the second air drawing portion are drawn into theinterior of the reflector in two different directions, desirably, in twodirections opposite to each other. Further, the streams of the coolingair separated by the first air drawing portion and the second airdrawing portion are guided to the fixing portion in two differentdirections.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, and novel features of the present inventionwill become more apparent upon reading the following detaileddescription of the embodiment along with the accompanying drawings.

FIGS. 1A and 1B are diagrams showing an arrangement of a projectorembodying the invention.

FIGS. 2A and 2B are diagrams showing an inner structure of the projectorembodying the invention.

FIG. 3 is a diagram showing an arrangement of an optical system in theembodiment.

FIGS. 4A and 4B are diagrams showing an arrangement of a prism unit inthe embodiment.

FIG. 5 is a diagram showing an arrangement of an attachment frame onwhich the prism unit in the embodiment is mounted.

FIGS. 6A and 6B are diagrams showing a state that the prism unit in theembodiment is fixedly mounted on the attachment frame.

FIGS. 7A and 7B are diagrams showing an arrangement of a cooling deviceof the optical system in the embodiment.

FIGS. 8A and 8B are diagrams showing an arrangement of an upper casingand first through third ducts in the embodiment.

FIGS. 9A and 9B are diagrams showing an arrangement of a lower casingand fourth through sixth ducts in the embodiment.

FIG. 10A is a perspective and elevational sectional view of a lamp unitin the embodiment, when viewed from a rear of the lamp unit.

FIG. 10B is a perspective and transverse sectional view of the lamp unitin the embodiment, when viewed from a front of the lamp unit.

FIG. 11 is a perspective view of the lamp unit in the embodiment, whenviewed from the front of the lamp unit.

FIG. 12A is a left side view of the lamp unit in the embodiment.

FIG. 12B is a rear view of the lamp unit in the embodiment.

FIG. 13A is a top plan view of the lamp unit in the embodiment.

FIG. 13B is a bottom plan view of the lamp unit in the embodiment.

FIG. 14 is a front view showing a state that the lamp unit in theembodiment is connected to a fan unit.

FIG. 15 is a perspective view of an upper cabinet in a state that aprism cover and a lamp cover in the embodiment are detached.

FIGS. 16A and 16B are diagrams showing an arrangement of the prism coverin the embodiment.

FIGS. 17A and 17B are diagrams showing an arrangement of the lamp coverin the embodiment.

FIGS. 18A and 18B are cross-sectional views showing essential parts ofthe upper cabinet in a state that the prism cover and the lamp cover aremounted on the upper cabinet in the embodiment.

FIGS. 19A and 19B are diagrams showing a state that the lamp cover inthe embodiment is opened.

FIG. 20 is a cross-sectional view showing essential parts of the uppercabinet for describing an operation to be performed for the lamp cover,in the case where the lamp cover in the embodiment is opened.

FIGS. 21A and 21B are diagrams showing a state that the prism cover inthe embodiment is opened.

The drawings are provided mainly for describing the present invention,and do not limit the scope of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, an embodiment of the invention is described referringto the drawings.

In this embodiment, a light source lamp 300 corresponds to a “lightsource” in the claims. An arc tube 301 corresponds to a “light emittingportion” in the claims. A reflector base 303 corresponds to a “fixingportion” in the claims. A first air outlet 407, a third air outlet 413,and an upper duct portion 415 correspond to a “first air drawingportion” in the claims. A second air outlet 409, a fourth air outlet414, and a lower duct portion 416 correspond to a “second air drawingportion” in the claims. A cooling fan 501 corresponds to a “first airsupply portion” in the claims. A cooling fan 502 corresponds to a“second air supply portion” in the claims. The description regarding thecorrespondence between the claims and the embodiment is merely anexample, and the claims are not limited by the description of theembodiment.

Entire Arrangement of Projector

FIGS. 1A and 1B are diagrams showing an arrangement of a projector. FIG.1A is a perspective view of the projector when viewed from a front ofthe projector. FIG. 1B is a perspective view of the projector whenviewed from a rear of the projector.

Referring to FIGS. 1A and 1B, the projector includes a cabinet 1 havinga substantially rectangular parallelepiped shape with a longer size inleft and right directions. The cabinet 1 is constituted of a lowercabinet 2 with an upper surface thereof being opened, and an uppercabinet 3 for covering the upper surface of the lower cabinet 2.

A projection opening 4 is formed in a central part on a front surface ofthe lower cabinet 2. A front portion of a projection lens 5 is exposedthrough the projection opening 4.

A left side surface of the lower cabinet 2 is constituted of an airinlet cover 6, except for a front end and a rear end of the left sidesurface. The air inlet cover 6 has a hinge structure (not shown) at alower end thereof, and is pivotally opened in the left direction aboutthe lower end (see FIGS. 2A and 2B). An air inlet 7 is formed in the airinlet cover 6. The air inlet 7 is constituted of a large number of slitholes.

An exhaust port 8 is formed in a right rear corner of the lower cabinet2. The exhaust port 8 is constituted of a large number of slit holes. AnAV terminal portion 9 is formed on a rear surface of the lower cabinet2, and an AV (Audio Visual) signal is inputted from the AV terminalportion 9.

The upper cabinet 3 has a prism cover 10 and a lamp cover 11. The prismcover 10 is a cover for covering a prism opening formed in the uppercabinet 3. The prism opening is used for e.g. replacement of a prismunit or adjustment of a polarizer. The lamp cover 11 is a cover forcovering a lamp opening formed in the upper cabinet 3. The lamp openingis used for replacement of a lamp unit. Upper surfaces of the prismcover 10 and the lamp cover 11 are formed flush with an upper surface ofthe upper cabinet 3. An attachment structure as to how the prism cover10 and the lamp cover 11 are attached to the upper cabinet 3 will bedescribed later.

An indicator portion 12 is formed on a right-side front end of the uppercabinet 3. The indicator portion 12 has plural LEDs. A user is notifiedof whether the projector is in an operation state or in a standby state,or notified of various error statuses by on/off states of the respectiveLEDs. For instance, the indicator portion 12 may notify the user of atiming when the lamp unit is to be replaced.

FIGS. 2A and 2B are diagrams showing an inner structure of theprojector. FIG. 2A is a perspective view of the projector in a statethat the upper cabinet 3 is detached. FIG. 2B is a perspective view ofthe projector in a state that a control circuit board 26, the AVterminal portion 9, and an air inlet member 22 are detached from thestate shown in FIG. 2A.

Referring to FIG. 2B, the lower cabinet 2 is internally provided with alamp unit 13, and an optical system 14 for modulating light from thelamp unit 13 to generate image light.

The lamp unit 13 is disposed at a central part on a right side surfaceof the lower cabinet 2 in such a manner that the lamp unit 13 isdetachably attached from above. The lamp unit 13 is constituted of alight source lamp 300, and a lamp holder 400 for holding the lightsource lamp 300 (see FIGS. 10A and 10B). A fan unit 15 is disposed infront of the lamp unit 13. The fan unit 15 supplies an air to cool thelight source lamp 300. The lamp holder 400 is formed with an air ductthrough which the cooling air from the fan unit 15 is guided to thelight source lamp 300. The detailed arrangement of the lamp unit 13 willbe described later.

The optical system 14 is disposed on the left of the lamp unit 13 and ina central part of the lower cabinet 2. The optical system 14 includes aprism unit 16. The prism unit 16 is disposed inside the lower cabinet 2in such a manner that the prism unit 16 is detachable from above. Thedetailed arrangement of the optical system 14 will be described later.

A lens shift unit 17 is disposed in front of the optical system 14. Theprojection lens 5 is mounted on the lens shift unit 17. The projectionlens 5 enlarges image light generated by the optical system 14, andprojects the enlarged image light onto a projection plane such as ascreen. The lens shift unit 17 shifts the projection lens 5 in up anddown directions and left and right directions by using a driving forceof a motor. By performing the above operation, the position of aprojected image can be adjusted.

A power source unit 18 is disposed behind the optical system 14. Thepower source unit 18 has a power source circuit, and supplies a powersource to each of the electrical components of the projector. A lampballast 19 is disposed at an upper portion of the power source unit 18.The lamp ballast 19 converts a power source supplied from the powersource unit 18 into a power source suitable for the light source lamp300, and supplies the converted power source to the light source lamp300.

The lower cabinet 2 is further internally provided with a cooling device20. The cooling device 20 has six cooling fans, and supplies theexternal air drawn in through the air inlet 7 to the exothermiccomponents of the optical system 14 such as the prism unit 16 to coolthe exothermic components. The detailed arrangement of the coolingdevice 20 will be described later.

A power source cooling fan 21 is disposed on the left of the powersource unit 18 and the lamp ballast 19. The power source cooling fan 21supplies an air to the power source unit 18 and the lamp ballast 19 tocool the power source unit 18 and the lamp ballast 19. An axial fan isused as the power source cooling fan 21, for example.

Next, referring to FIG. 2A, the air inlet member 22 is mounted on a leftside portion of the lower cabinet 2. The air inlet member 22 isconstituted of a frame member 23, and a filter member 24 mounted on theframe member 23. An air inlet (not shown) is formed in a surface of theframe member 23 opposing to the filter member 24. The filter member 24is covered by the air inlet cover 6. In replacing the filter member 24,the air inlet cover 6 is opened, and the filter member 24 is detachedfrom the frame member 23.

An air flow velocity sensor (not shown) is disposed in the air inletmember 22 at a position downstream of the filter member 24. Adetermination is made as to whether the filter member 24 is clogged,based on an air flow velocity to be detected by the air flow velocitysensor, and the user is notified of whether the filter member 24 isclogged by e.g. the indicator portion 12.

In response to activation of e.g. the lamp unit 13, the cooling device20, and the power source cooling fan 21, the external air is drawn inthrough the air inlet 7 of the air inlet cover 6, the filter member 24,and the air inlet of the frame member 23.

An exhaust fan 25 is disposed at the right rear corner of the lowercabinet 2. The exhaust fan 25 is disposed in oblique direction withrespect to the right side surface and the rear surface of the lowercabinet 2, and an intake surface of the exhaust fan 25 is directedobliquely leftward in the front direction. An axial fan is used as theexhaust fan 25, for example.

In response to activation of the exhaust fan 25, as shown in FIG. 2B,the cooling air which has cooled the power source unit 18 and the lampballast 19 is drawn in toward the exhaust fan 25 in the direction fromthe left side, and the cooling air which has cooled the light sourcelamp 300 and exited the lamp unit 13 is drawn in toward the exhaust fan25 in the direction from the front side. Further, the cooling air whichhas cooled the optical system 14 is drawn in toward the exhaust fan 25obliquely leftward from the front direction. In performing the aboveoperation, since the intake surface of the exhaust fan 25 is directedobliquely leftward in the front direction, the cooling air to besupplied in the three directions i.e. from the side of the lamp unit 13,the side of the power source unit 18, and the side of the optical system14 is easily drawn in toward the exhaust fan 25. Thus, the abovearrangement enables to smoothly discharge the cooling air which hascooled the exothermic components to the exterior of the projector,thereby advantageously cooling the exothermic components.

Further, since the air inlet 7 is formed in a side surface (the leftside surface) opposite to the position where the exhaust fan 25 isdisposed, the external air drawn in through the air inlet 7 is drawn intoward the exhaust fan 25, after having been sufficiently used forcooling the lamp unit 13, the power source unit 18, and the opticalsystem 14. Thus, the arrangement is further advantageous in cooling theexothermic components.

Furthermore, the cooling air to be supplied in the three directions isnot discharged immediately after exiting the exhaust fan 25, but isdischarged after having been sufficiently mixed in a space between anexhaust surface of the exhaust fan 25 and a corner of the lower cabinet2. The light source lamp 300 is heated to an exceedingly hightemperature, as compared with the power source unit 18 or a like member.Accordingly, the cooling air from the side of the lamp unit 13 is heatedto an exceedingly high temperature, as compared with the cooling air inthe other directions. However, as described above, since the cooling airwhich has been drawn in toward the exhaust fan 25 from the side of thelamp unit 13 is discharged after having been sufficiently mixed with thecooling air in the other directions, the temperature of the dischargedair can be lowered.

Furthermore, since the exhaust fan 25 is disposed in oblique direction,it is possible to dispose a largest possible exhaust fan in a limitedspace enclosed by the corner of the lower cabinet 2, the lamp unit 13,and the power source unit 18.

Furthermore, since the exhaust port 8 is formed in the corner of thelower cabinet 2, it is possible to increase the opening area of theexhaust port 8. Thus, a more smooth air discharge operation can beperformed.

The exhaust fan 25 may be disposed at a corner other than the right rearcorner, depending on the dispositions of the respective constituentcomponents in the lower cabinet 2.

As shown in FIG. 2A, the control circuit board 26 is disposed above theoptical system 14 and the power source unit 18. The control circuitboard 26 is provided with a control circuit for controlling drivingcomponents such as liquid crystal panels and the light source lamp 300.The control circuit board 26 is cut away at a position above the prismunit 16. In this arrangement, the prism unit 16 is detachably attachedfrom above in a state that the control circuit board 26 is mounted.

Arrangement of Optical System

FIG. 3 is a diagram showing an arrangement of the optical system 14.

White light emitted from the light source lamp 300 is transmittedthrough a condenser lens 101, a fly-eye integrator 102, and a PBS array103. The fly-eye integrator 102 makes a light amount distribution oflight of each of the colors to be irradiated to liquid crystal panels(which will be described later) uniform. The PBS array 103 alignspolarization directions of light of the respective colors toward adichroic mirror 105 in one direction.

Light transmitted through the PBS array 103 is transmitted through acondenser lens 104, and entered into the dichroic mirror 105.

The dichroic mirror 105 reflects only light (hereinafter, called as “Blight”) in a blue wavelength band, and transmits light (hereinafter,called as “G light”) in a green wavelength band and light (hereinafter,called as “R light”) in a red wavelength band, out of the light enteredinto the dichroic mirror 105.

B light reflected on the dichroic mirror 105 is irradiated onto a liquidcrystal panel 108 for B light in a proper irradiation state by a lensfunction by the condenser lens 104 and a condenser lens 106, andreflection on a reflection mirror 107. The liquid crystal panel 108 isdriven in accordance with an image signal for B light to modulate the Blight depending on a driven state of the liquid crystal panel 108. Oneincident-side polarizer 109 is disposed on the incident side of theliquid crystal panel 108. B light is irradiated onto the liquid crystalpanel 108 through the incident-side polarizer 109. Further, twooutput-side polarizers 110 are disposed on the output side of the liquidcrystal panel 108, and B light emitted from the liquid crystal panel 108is entered into the output-side polarizers 110.

G light and R light transmitted through the dichroic mirror 105 areentered into a dichroic mirror 111. The dichroic mirror 111 reflects theG light and transmits the R light.

G light reflected on the dichroic mirror 111 is irradiated onto a liquidcrystal panel 113 for G light in a proper irradiation state by a lensfunction by the condenser lens 104 and a condenser lens 112. The liquidcrystal panel 113 is driven in accordance with an image signal for Glight to modulate the G light depending on a driven state of the liquidcrystal panel 113. One incident-side polarizer 114 is disposed on theincident side of the liquid crystal panel 113, and G light is irradiatedonto the liquid crystal panel 113 through the incident-side polarizer114. Further, two output-side polarizers 115 are disposed on the outputside of the liquid crystal panel 113, and G light emitted from theliquid crystal panel 113 is entered into the output-side polarizers 115.

R light transmitted through the dichroic mirror 111 is irradiated onto aliquid crystal panel 121 for R light in a proper irradiation state by alens function by the condenser lens 104, a condenser lens 116, and relaylenses 117 and 118, and reflection on reflection mirrors 119 and 120.The liquid crystal panel 121 is driven in accordance with an imagesignal for R light to modulate the R light depending on a driven stateof the liquid crystal panel 121. One incident-side polarizer 122 isdisposed on the incident side of the liquid crystal panel 121, and Rlight is irradiated onto the liquid crystal panel 121 through theincident-side polarizer 122. Further, two output-side polarizers 123 aredisposed on the output side of the liquid crystal panel 121, and R lightemitted from the liquid crystal panel 121 is entered into theoutput-side polarizers 123.

B light, G light, and R light modulated by the liquid crystal panels108, 113, and 121 are transmitted through the output-side polarizers110, 115, and 123, and entered into a dichroic prism 124. The dichroicprism 124 reflects B light and R light, and transmits G light, out ofthe B light, the G light, and the R light, to thereby combine the Blight, the G light, and the R light. Thus, image light after the colorcombination is projected toward the projection lens 5 from the dichroicprism 124.

An imager constituting the optical system 14 may be a reflective liquidcrystal panel or an MEMS device, in place of the transmissive liquidcrystal panels 108, 113, and 121. Further, the optical system 14 may beconstituted of e.g. a single-panel optical system incorporated with animager and a color wheel, in place of the three-panel optical systemincorporated with three imagers as described above.

Attachment Structure of Prism Unit

FIGS. 4A and 4B are diagrams showing an arrangement of the prism unit16. FIG. 4A is a perspective view of the prism unit 16, and FIG. 4B is abottom plan view of the prism unit 16.

The prism unit 16 is assembled into one unit by assembling the liquidcrystal panels 108, 113, and 121, the output-side polarizers 110, 115,and 123, and the dichroic prism 124 on a prism holder 125. The liquidcrystal panels 108, 113, and 121 are fixedly attached to the prismholder 125 via brackets 126.

An attachment leg 127 is provided at three positions on a bottom portionof the prism holder 125. Each of the attachment legs 127 is formed withan attachment hole 128 and a positioning hole 129. Further, an insertionhole 130 is formed in a central part on a bottom surface of the prismholder 125. An inwardly protruding annular flange portion 131 is formedat an entrance of the insertion hole 130.

FIG. 5 is a perspective view showing an arrangement of an attachmentframe 132 on which the prism unit 16 is mounted.

The attachment frame 132 on which the prism unit 16 is mounted isprovided in the lower cabinet 2. The attachment frame 132 is providedwith three bosses 133 corresponding to the three attachment holes 128 ofthe prism holder 125. The attachment frame 132 is further provided withpositioning projections 134 corresponding to the three positioning holes129 of the prism holder 125. The attachment frame 132 is furthermoreprovided with a stopper pin 135 corresponding to the insertion hole 130.

FIG. 6A is a perspective view showing a state that the prism unit 16 isfixedly mounted on the attachment frame 132. FIG. 6B is across-sectional view showing essential parts of the prism unit 16 in astate that the stopper pin 135 is received in the insertion hole 130.

The prism unit 16 is placed on the attachment frame 132 in such a mannerthat the positioning projections 134 are received in the correspondingpositioning holes 129. Thereby, the attachment holes 128 of the prismholder 125 are aligned with the corresponding bosses 133. In thealignment operation, the stopper pin 135 is fitted into the insertionhole 130 of the prism unit 16. Then, by fastening the attachment legs127 of the prism unit 125 to the bosses 133 by screws, the prism unit 16is fixedly mounted on the attachment frame 132.

As shown in FIG. 6B, an engaging portion 136 which is flexed in thecircumferential direction is formed at a lead end of the stopper pin135. By inserting the stopper pin 135 in the insertion hole 130, theengaging portion 136 is engaged with the flange portion 131. In thisstate, there is no likelihood that the stopper pin 135 may come out ofthe insertion hole 130, even if a force substantially equal to theweight of the prism unit 16 is exerted in a direction of disengaging thestopper pin 135 from the insertion hole 130.

The installation manner of a projector includes a ceiling mount, whereina projector is suspended from a ceiling, in addition to a fixed mount,wherein a projector is mounted on a floor surface or a desk surface. Inthe case of the ceiling mount, a projector is mounted upside down.

In this embodiment, in the case where a projector is suspended from aceiling, there is no likelihood that the prism unit 16 may come out ofthe attachment frame 132 by the weight thereof, even if screws areunfastened from the bosses 133. Accordingly, mounting/dismountingoperations of the prism unit 16 can be easily performed in replacing theprism unit 16.

In this embodiment, the stopper pin 135 as an independent member isfixedly attached to the attachment frame 132. Alternatively, a stopperportion formed with the engaging portion 136 may protrude from theattachment frame 132. In the modification, the stopper portion may beintegrally formed with the attachment frame 132.

Arrangement of Cooling Device of Optical System

FIGS. 7A and 7B, FIGS. 8A and 8B, and FIGS. 9A and 9B are diagramsshowing an arrangement of the cooling device 20 of the optical system14. FIGS. 7A and 7B are perspective views of the cooling device 20. InFIG. 7A, only the prism unit 16 and the PBS array 103 in the arrangementof the optical system 14 are shown together with the cooling device 20.FIGS. 8A and 8B are respectively a top plan view and a bottom plan viewof an upper casing 202, a first duct 210, a second duct 211, and a thirdduct 212. FIGS. 9A and 9B are respectively a top plan view and a bottomplan view of a lower casing 203, a fourth duct 217, a fifth duct 218,and a sixth duct 219.

The cooling device 20 has a fan casing 201. The fan casing 201 isconstituted of the upper casing 202 and the lower casing 203. A rearsurface and a bottom surface of each of the upper casing 202 and thelower casing 203 are opened. The lower casing 203 is mounted on thebottom surface of the lower cabinet 2, and the upper casing 202 ismounted on the lower casing 203.

The interior of the upper casing 202 is divided into three housingportions (a first housing portion 204, a second housing portion 205, anda third housing portion 206) by two partition walls 202 a and 202 b.Likewise, the interior of the lower casing 203 is divided into threehousing portions (a fourth housing portion 207, a fifth housing portion208, and a sixth housing portion 209) by two partition walls 203 a and203 b.

The first housing portion 204, the second housing portion 205, and thethird housing portion 206 of the upper casing 202 are respectivelyconnected to the first duct 210, the second duct 211, and the third duct212. Each of the first duct 210, the second duct 211, and the third duct212 has a bottom surface thereof opened, and extends to a position belowthe prism unit 16. The first duct 210, the second duct 211, and thethird duct 212 are integrally formed with the upper casing 202 by aresin material.

An air outlet 213 is formed in a lead end of the first duct 210. The airoutlet 213 is directed toward the incident-side polarizer 114 and theliquid crystal panel 113 for G light. A partition member 213 a is formedin the middle of an exit of the air outlet 213 to guide the cooling airto each of the incident-side polarizer 114 and the liquid crystal panel113. An air outlet 214 is formed in a lead end of the second duct 211.The air outlet 214 is directed toward the output-side polarizers 115 forG light. Two air outlets 215 and 216 are formed in a lead end of thethird duct 212. The air outlet 215 is directed to the incident-sidepolarizer 122 and the liquid crystal panel 121 for R light, and the airoutlet 216 is directed to the output-side polarizers 123 for R light.

The fourth housing portion 207, the fifth housing portion 208, and thesixth housing portion 209 of the lower casing 203 are respectivelyconnected to the fourth duct 217, the fifth duct 218, and the sixth duct219. Each of the fourth duct 217, the fifth duct 218, and the sixth duct219 has a bottom surface thereof opened. The fourth duct 217 extends toa position below the PBS array 103, and the fifth duct 218 and the sixthduct 219 each extends to a position below the prism unit 16. The fourthduct 217, the fifth duct 218, and the sixth duct 219 are integrallyformed with the lower casing 203 by a resin material.

An air outlet 220 is formed in a lead end of the fourth duct 217. Theair outlet 220 is directed toward the PBS array 103. An air outlet 221is formed in a lead end of the fifth duct 218. The air outlet 221 isdirected toward the incident-side polarizer 109 and the liquid crystalpanel 108 for B light. An air outlet 222 is formed in a lead end of thesixth duct 219. The air outlet 222 is directed to the output-sidepolarizers 110 for B light. Another air outlet 223 is formed adjacent tothe air outlet 220 for the PBS array 103. The air outlet 223 iscommunicated with a cooling fan (not shown) different from the coolingdevice 20, and the cooling air from the cooling fan is drawn through theair outlet 223. An air deflector 220 a is provided at exits of the airoutlets 220 and 223 to guide the air toward the PBS array 103.

As shown in FIG. 9A, bottom surface members 210 b, 211 b, and 212 bcorresponding to the first duct 210, the second duct 211, and the thirdduct 212 are integrally formed on upper surfaces of the fourth duct 217,the fifth duct 218, and the sixth duct 219. When the upper casing 202 ismounted on the lower casing 203, the bottom surfaces of the first duct210, the second duct 211, and the third duct 212 are closed by thecorresponding bottom surface members 210 b, 211 b, and 212 b, whereby anair duct having an airtight structure is formed. On the other hand, whenthe lower casing 203 is mounted on the lower cabinet 2, the bottomsurfaces of the fourth duct 217, the fifth duct 218, and the sixth duct219 are closed by a bottom member (not shown) which is integrally formedwith the lower cabinet 2, whereby an air duct having an airtightstructure is formed.

Cooling fans (first through sixth fans 224 through 229) are respectivelydisposed in the first through the sixth housing portions 204 through 209of the fan casing 201. As shown in FIGS. 8B and 9B, air outlets 224 athrough 229 a of the respective cooling fans 224 through 229 areconnected to entrances 210 a through 212 a of the corresponding firstthrough the third ducts 210 through 212, and entrances 217 a through 219a of the corresponding fourth through the sixth ducts 217 through 219.Each of the cooling fans 224 through 229 is a centrifugal fan having thesame performance, with both surfaces thereof being formed into intakesurfaces. Air inlets 224 b through 229 b are formed on both ends of eachof the cooling fans 224 through 229.

Each of the first fan 224, the second fan 225, and the third fan 226 isfixedly fastened to an attachment boss 230 provided on the upper surfaceof the lower casing 203 by a screw. Likewise, each of the fourth fan227, the fifth fan 228, and the sixth fan 229 is fixedly fastened to anattachment boss 231 provided on the bottom surface of the lower cabinet2 by a screw. In a state that the first through the sixth fans 224through 229 are fixedly attached to the attachment bosses 230 and 231, aclearance for drawing in the external air is formed between upper endsurface of each of the cooling fans 224 through 229 and the uppersurface of each of the first through the sixth housing portions 204through 209, and a clearance for drawing in the external air is formedbetween the bottom surface of each of the cooling fans 224 through 229and the bottom surface of each of the first through the sixth housingportions 204 through 209.

As shown in FIG. 2A, the rear surface of the fan casing 201 is coveredby the air inlet member 22.

In the above arrangement, in response to activation of the cooling fans224 through 229, the external air is drawn into the cabinet 1 throughthe air inlet member 22. The drawn external air passes through the upperand lower clearances of the first through the sixth housing portions 204through 209 from the rear of the fan casing 201, and is drawn to thecooling fans 224 through 229 through the air inlets 224 b through 229 bformed in both end surfaces of each of the cooling fans 224 through 229.

The cooling air from the first fan 224 passes through the first duct210, and is drawn in toward the incident-side polarizer 114 and theliquid crystal panel 113 for G light through the air outlet 213. As aresult of the above operation, the incident-side polarizer 114 and theliquid crystal panel 113 are cooled. The cooling air from the second fan225 passes through the second duct 211, and is drawn in toward theoutput-side polarizers 115 for G light through the air outlet 214. As aresult of the above operation, the output-side polarizers 115 arecooled. The cooling air from the third fan 226 passes through the thirdduct 212, and is drawn in toward the incident-side polarizer 122 and theliquid crystal panel 121 for R light through the air outlet 215, and isalso drawn in toward the output-side polarizers 123 for R light throughthe air outlet 216. As a result of the above operation, theincident-side polarizer 122, the liquid crystal panel 121, and theoutput-side polarizers 123 are cooled.

The cooling air from the fourth fan 227 passes through the fourth duct217, and is drawn in toward the PBS array 103 through the air outlet220. As a result of the above operation, the PBS array 103 is cooled.The cooling air from the fifth fan 228 passes through the fifth duct218, and is drawn in toward the incident-side polarizer 109 and theliquid crystal panel 108 for B light through the air outlet 221. As aresult of the above operation, the incident-side polarizer 109 and theliquid crystal panel 108 are cooled. The cooling air from the sixth fan229 passes through the sixth duct 219, and is drawn in toward theoutput-side polarizers 110 for B light through the air outlet 222. As aresult of the above operation, the output-side polarizers 110 arecooled.

In the prism unit 16, concerning the light amounts to be absorbed at thetime of modulation, the calorific value generated by a green imager(constituted of the liquid crystal panel 113, the incident-sidepolarizer 114, and the output-side polarizers 115) becomes largest, andthe calorific value generated by a blue imager (constituted of theliquid crystal panel 108, the incident-side polarizer 109, and theoutput-side polarizers 110) becomes second largest. As compared with thecalorific values generated by these imagers, the calorific valuegenerated by a red imager (constituted of the liquid crystal panel 121,the incident-side polarizer 122, and the output-side polarizers 123) issmall. As compared with the calorific values generated by the liquidcrystal panels 108, 113, and 121, and the incident-side polarizers 109,114, and 122, the calorific values generated by the output-sidepolarizers 110, 115, and 123 are large. Thus, the calorific values aredifferent from each other depending on the imagers.

In this embodiment, applied voltages to the second fan 225 and the thirdfan 226 are set equal to each other. This is because there is nosignificant difference in the required air volume between the second fan225 and the third fan 226. Further, applied voltages to the first fan224, the fifth fan 228, and the sixth fan 229 are set equal to eachother. This is because there is no significant difference in therequired air volume between the first fan 224, the fifth fan 228, andthe sixth fan 229.

Further, applied voltages to the second fan 225, the third fan 226, andthe fourth fan 227 are set higher than the applied voltages to the firstfan 224, the fifth fan 228 and the sixth fan 229. The applied voltage tothe second fan 225 is set high, because the calorific value generated bythe output-side polarizers 115 for G light is largest, and it isnecessary to increase the air volume for the output-side polarizers 115for G light. The air volume for the third fan 226 is set high, becausethe red imager constituted of the incident-side polarizer 122, theliquid crystal panel 121, and the output-side polarizers 123 is cooledonly by the third fan 226, and it is necessary to increase the airvolume for the red imager.

As described above, by setting the air volumes of the second fan 225 andthe third fan 226 larger than the air volumes of the first fan 224, thefifth fan 228 and the sixth fan 229, it is possible to efficiently coolthe output-side polarizers 115 for G light, and the red imager.

The applied voltage to the fourth fan 227 is set equal to the appliedvoltages to the second fan 225 and the third fan 226. This is becausethe length of the fourth duct 217 extending to the PBS array 103 islonger than the lengths of the other air ducts, and a pressure loss ofthe fourth duct 217 is large.

As described above, in this embodiment, the cooling air from the thirdfan 226 is supplied to the red imager, the cooling air from the thirdfan 224 and the second fan 225 is supplied to the green imager, and thecooling air from the fifth fan 228 and the sixth fan 229 is supplied tothe blue imager. Thus, the embodiment is configured to supply thecooling air from the individual cooling fans to each of the imagers.Accordingly, it is possible to set the air volumes of the cooling fans224, 225, 226, 228, and 229 depending on the calorific values generatedby the respective imagers. This is advantageous in efficiently coolingthe prism unit 16, while reducing noises and electric power consumption.

Further, with respect to the green imager, the cooling air from thefirst fan 224 is supplied to the air outlet 213 directed toward theincident-side polarizer 114 and the liquid crystal panel 113, and thecooling air from the second fan 225 is supplied to the air outlet 214directed toward the output-side polarizers 115. Thus, since the coolingair is supplied from the plural cooling fans to the green imager whosecalorific value becomes largest, it is possible to secure a sufficientair volume to thereby sufficiently cool the target imager. Further, bysetting the air volume of the first fan 224 depending on the calorificvalue generated by the incident-side polarizer 114 and the liquidcrystal panel 113, and setting the air volume of the second fan 225depending on the calorific value generated by the output-side polarizers115, it is possible to efficiently cool these optical elements.

Similarly, with respect to the blue imager, the cooling air from thefifth fan 228 is supplied to the air outlet 221 directed to theincident-side polarizer 109 and the liquid crystal panel 108, and thecooling air from the sixth fan 229 is supplied to the air outlet 222directed to the output-side polarizers 110. Thus, since the cooling airis supplied from the plural cooling fans to the blue imager whosecalorific value is second largest to the green imager, it is possible tosecure a sufficient air volume to thereby sufficiently cool the targetimager. Further, by setting the air volume of the fifth fan 228depending on the calorific value generated by the incident-sidepolarizer 109 and the liquid crystal panel 110, and setting the airvolume of the sixth fan 229 depending on the calorific value generatedby the output-side polarizers 110, it is possible to efficiently coolthese optical elements.

In the case where the projector is configured to supply the cooling airfrom a single cooling fan to the two air outlets 213 and 214 (221 and222) for the green (blue) imager through individual ducts, a large-sizedcooling fan is necessary. An increase in the size of a cooling fanresults in an increase in the size of an air outlet. As a result, adifference in opening area between the air outlet of the cooling fan,and the air outlets 213 and 214 (221 and 222) is increased. Then, theair flow rates of the respective air passages from the cooling fan tothe air outlets 213 and 214 (221 and 222) are increased, whichresultantly increases the pressure loss, and lowers the air supply rateof the cooling fan.

In this embodiment, since each of the cooling fans 224 and 225 (228 and229) individually supplies the cooling air to the air outlets 213 and214 (221 and 222) for the green (blue) imager, it is possible to reducethe size of the individual cooling fans 224 and 225 (228 and 229). Thus,since it is possible to reduce a difference in opening area between theair outlets 224 a and 225 a (228 a and 229 a) of the cooling fans 224and 225 (228 and 229), and the air outlets 213 and 214 (221 and 222), itis possible to enhance the air supply rate of the cooling fans 224 and225 (228 and 229).

In this embodiment, the six cooling fans 224 through 229 are dividedinto two groups, in each of which a required air volume is approximateto each other, and an applied voltage is set for each of the groups.Alternatively, for instance, the six cooling fans 224 through 229 may bedivided into three or more groups depending on a required air volume,and an applied voltage may be set with respect to each of the groups.Further alternatively, applied voltages may be set individually withrespect to all the six cooling fans 224 through 229.

Further alternatively, temperatures of the optical elements of the prismunit 16, and the PBS array 103 may be detected, and applied voltages tothe cooling fans 224 through 229 may be changed, based on the detectedtemperatures. The modification is further advantageous in reducingnoises and reducing electric power consumption.

Further, in this embodiment, one cooling fan (the third fan) is providedfor both of the air outlets 215 and 216. Alternatively, a cooling fanmay be provided for each of the air outlets 215 and 216. Furtheralternatively, three or more cooling fans may be provided for at leastone of the imagers, as necessary.

Cooling Structure of Lamp Unit

FIGS. 10A and 10B, FIG. 11, FIGS. 12A and 12B, FIGS. 13A and 13B, andFIG. 14 are diagrams for describing a cooling structure of the lamp unit13. FIG. 10A is a perspective and elevational sectional view of the lampunit 13, when viewed from a rear of the lamp unit 13. FIG. 10B is aperspective and transverse sectional view of the lamp unit 13, whenviewed from a front of the lamp unit 13. FIG. 11 is a perspective viewof the lamp unit 13, when viewed from the front of the lamp unit 13.FIGS. 12A and 12B are respectively a left side view and a rear view ofthe lamp unit 13. FIGS. 13A and 13B are respectively a top plan view anda bottom view of the lamp unit 13. FIG. 14 is a front view showing astate that the lamp unit 13 is connected to the fan unit 15. In FIG. 14,the general contour of a housing 503 is shown by the dotted line so thatcooling fans 501 and 502 disposed in the fan unit 15 can be seen.

Referring to FIGS. 10A through 14, the lamp unit 13 is constituted ofthe light source lamp 300, and the lamp holder 400 for holding the lightsource lamp 300.

The light source lamp 300 is provided with an arc tube 301 and areflector 302. In this embodiment, a metal halide lamp is used as thearc tube 301. Alternatively, other lamp such as an ultra high-pressuremercury lamp or a xenon lamp may be used. An inner surface of thereflector 302 is formed into a paraboric shape to reflect white lightemitted from the arc tube 301 on the inner surface of the reflector 302,and guide the reflected light in the forward direction.

A reflector base 303 made of e.g. plaster is formed on a rear end of thereflector 302 to fixedly mount the arc tube 301 on the reflector 302.The arc tube 301 has a seal portion 304 at an inner position of thereflector base 303.

The lamp holder 400 is provided with a holder main body 401, an upperplate 402 mounted on a rear end of an upper surface of the holder mainbody 401, and a bottom plate 403 mounted on a rear end of a bottomsurface of the holder main body 401.

An emission window 404 through which light from the light source lamp300 is emitted is formed in a front surface of the holder main body 401.A heat resistant glass plate 405 is fitted in the emission window 404. Arear surface of the holder main body 401 is opened, and the light sourcelamp 300 is mounted in the opening from a rear side.

A guide piece 406 is formed on both ends of a front portion of theholder main body 401. A guide member (not shown) having verticallyextending guide grooves is formed in the lower cabinet 2 at a housingposition of the lamp unit 13. The guide pieces 406 are fitted in theguide grooves from above in housing the lamp unit 13 in the lowercabinet 2.

A first air outlet 407 is formed in the upper surface of the holder mainbody 401. A first air deflector 408 extending obliquely downward inrearward direction is provided in the first air outlet 407. Further, asecond air outlet 409 is formed in the bottom surface of the holder mainbody 401. A second air deflector 410 extending obliquely upward inrearward direction is provided in the second air outlet 409. Exhaustports 411 and 412 are formed in a right side surface and a left sidesurface of the holder main body 401, respectively. Filters 411 a and 412a in the form of a mesh are provided in the exhaust ports 411 and 412,respectively, to prevent pieces of the arc tube 301 from coming out ofthe projector, in case that the arc tube 301 be damaged or broken.

A third air outlet 413 is formed in the upper plate 402 at a positionsubstantially right above the reflector base 303. Further, a fourth airoutlet 414 is formed in the bottom plate 403 at a position substantiallyright below the reflector base 303.

An upper duct portion 415 is mounted on an upper surface of the lampholder 400. As shown in FIG. 13A, the upper duct portion 415 has asubstantially T-shape in plan view to guide the cooling air that hasbeen drawn in through an entrance 415 a formed in a right side surfaceof the upper duct portion 415 to the first air outlet 407 and the thirdair outlet 413. On the other hand, a lower duct portion 416 is mountedon a bottom surface of the lamp holder 400. As shown in FIG. 13B, thelower duct portion 416 has a substantially T-shape in plan view to guidethe cooling air that has been drawn in through an entrance 416 a formedin a right side surface of the lower duct portion 416 to the second airoutlet 409 and the fourth air outlet 414.

Similarly to the filters 411 a and 412 a, filters 415 b and 416 b in theform of a mesh are provided in the upper duct portion 415 at a positionnear the first air outlet 407 and in the lower duct portion 416 at aposition near the second air outlet 409, respectively, to prevent piecesof the arc tube 301 from coming out of the projector, in case that thearc tube 301 be damaged or broken.

As shown in FIG. 14, the fan unit 15 is disposed in the housing 503 in astate that two cooling fans 501 and 502 are vertically stacked one overthe other. When the lamp unit 13 is mounted in the lower cabinet 2, theentrance 415 a of the upper duct portion 415 is connected to an upperexit 504 of the housing 503, and the entrance 416 a of the lower ductportion 416 is connected to a lower exit 505 of the housing 503.

In the above arrangement, in response to activation of the cooling fans501 and 502, cooling airs generated by the cooling fans 501 and 502 arerespectively allowed to flow through the upper duct portion 415 and thelower duct portion 416.

In FIGS. 10A and 10B, flows of the cooling air are shown by the arrows.The cooling air through the upper duct portion 415 is branched out inthe duct portion into a flow in the forward direction and a flow in therearward direction. The flow of the cooling air in the forward directionis passed through the filter 415 b, drawn into the holder main body 401through the first air outlet 407, has its direction changed by the firstair deflector 408, and flows into the reflector 302. Further, thecooling air through the lower duct portion 416 is branched out in theduct portion into a flow in the forward direction and a flow in therearward direction. The flow of the cooling air in the forward directionis passed through the filter 416 b, drawn into the holder main body 401through the second air outlet 409, has its direction changed by thesecond air deflector 410, and flows into the reflector 302. The interiorof the reflector 302 is cooled by the flows of the cooling air whichhave flown into the reflector 302 from both sides i.e. from the upperand lower duct portions. Thereafter, the cooling air in the reflector302 is passed through the filters 411 a and 412 a, and discharged to theexterior of the lamp unit 13 through the exhaust ports 411 and 412.

On the other hand, the flow of the cooling air in the rearward directionin the upper duct portion 415 is drawn in through the third air outlet413, and impinges on the reflector base 303 of the light source lamp 300from above. Further, the flow of the cooling air in the rearwarddirection in the lower duct portion 416 is drawn in through the fourthair outlet 414, and impinges on the reflector base 303 of the lightsource lamp 300 from below. As a result of the above operation, thereflector base 303 is cooled from both sides i.e. from the upper andlower duct portions, and the seal portion 304 is cooled via thereflector base 303.

As described above, the cooling air which has exited the lamp unit 13 isdischarged to the exterior of the cabinet 1 by the exhaust fan 25.

The upper portion of the light source lamp 300 is heated to a hightemperature, as compared with the lower portion of the light source lamp300 at the time of light emission, due to an influence of agravitational force. In the case where the projector is mounted in afixed position, the lamp unit 13 is brought to a state as shown in FIG.10A, and a portion of the light source lamp 300 corresponding to theupper duct portion 415 is heated to a high temperature, as compared witha portion of the light source lamp 300 corresponding to the lower ductportion 416. On the other hand, in the case where the projector issuspended from a ceiling, the lamp unit 13 is brought to a stateopposite to the state shown in FIG. 10A, and the portion of the lightsource lamp 300 corresponding to the lower duct portion 416 is heated toa high temperature, as compared with the portion of the light sourcelamp 300 corresponding to the upper duct portion 415.

In this embodiment, since the flows of the cooling air branched out bythe upper duct portion 415 and the lower duct portion 416 are guidedinto the reflector 302 from both sides i.e. from the upper and lowerduct portions, it is possible to efficiently cool a high-temperatureportion of the light source lamp 300, without depending on whether theprojector is mounted in a fixed position or mounted from a ceiling.

In the case where the projector is mounted in a fixed position, it isdesirable to set the air volume of the cooling fan 501 for supplying theair to the upper duct portion 415 higher than the air volume of thecooling fan 502 for supplying the air to the lower duct portion 416 toefficiently cool the portion of the light source lamp 300 correspondingto the upper duct portion 415. On the other hand, in the case where theprojector is mounted from a ceiling, it is desirable to set the airvolume of the cooling fan 502 higher than the air volume of the coolingfan 501 to efficiently cool the portion of the light source lamp 300corresponding to the lower duct portion 416.

Further, in the light source lamp 300, the seal portion 304 is heated toa high temperature by heat generation in the arc tube 301 resulting fromlight emission of the arc tube 301. If the seal portion 304 isexceedingly heated, the seal portion 304 may be deteriorated, with theresult that the performance of the light source lamp 300 may bedeteriorated. Since the seal portion 304 is disposed at a positionrelatively away from the inner surface of the reflector 302, the sealportion 304 may not be sufficiently cooled by the cooling air that hasbeen draw into the interior of the reflector 302. It may be possible toenhance the cooling performance by increasing the air volume of thecooling air. However, an enhanced cooling performance may excessivelycool the arc tube 301, which may obstruct a normal light emission.

In this embodiment, since the flows of the cooling air which havebranched out by the upper duct portion 415 and the lower duct portion416 are directly supplied to the reflector base 303 from both sides i.e.from the upper and lower duct portions, the entirety of the reflectorbase 303 is efficiently cooled, and the seal portion 304 is efficientlycooled via the reflector base 303. Thus, it is possible to preventlowering of the performance of the light source lamp 300 due todeterioration of the seal portion 304.

Attachment Structure of Prism Cover and Lamp Cover

FIG. 15 is a perspective view of the upper cabinet 3 in a state that theprism cover 10 and the lamp cover 11 are detached.

A recess 601 in which the prism cover 10 and the lamp cover 11 aremounted is formed in an area of the upper cabinet 3 from a central partto a right side surface of the upper cabinet 3. The recess 601 has afirst area 601 a where the prism cover 10 is mounted, and a second area601 b where the lamp cover 11 is mounted.

A prism opening 602 is formed in the first area 601 a. The prism opening602 is formed at a position substantially right above the prism unit 16disposed in the lower cabinet 2, and has a size capable of mounting anddismounting the prism unit 16.

Guide ribs 603 are formed at two positions on each of a front wallsurface and a rear wall surface of the first area 601 a. Predeterminedclearances are formed between the guide ribs 603 and a bottom surface ofthe recess 601. Further, an insertion hole 604 is formed at twopositions on a left wall surface of the first area 601 a. Furthermore, anut 605 is embedded in upward direction in a central part on a right endof the first area 601 a, and a screw hole of the nut 605 faces upward.

A lamp opening 606 is formed in the second area 601 b. The lamp opening606 is formed at a position substantially right above the lamp unit 13disposed in the lower cabinet 2, and has a size capable of mounting anddismounting the lamp unit 13. A pair of guide portions 607 is formed ona front edge and a rear edge of the lamp opening 606. Each of the pairedguide portions 607 is constituted of two ribs arranged side by side intransverse direction with a predetermined clearance. When the lamp unit13 is housed in the lower cabinet 2, the guide pieces 406 of the lampholder 400 are guided between the respective rib pairs.

In the second area 601 b, the lamp opening 606, and left and rightportions of the lamp opening 606 are recessed from the first area 601 a.An insertion hole 608 is formed at two positions in a wall surfacecorresponding to the step difference between the first area 601 a andthe second area 601 b.

A transversely extending guide groove 609 is formed in each of the frontedge and the rear edge of the second area 601 b. A transverselyextending guide hole 609 a is formed in a side surface of each of theguide grooves 609. Further, an opening 609 b for passing a stem portion808 of the lamp cover 11 is formed at an outer position substantially inthe middle of each of the guide grooves 609.

A nut 610 is embedded in transverse direction in a right end of thesecond area 601 b, and a screw hole of the nut 610 faces transverselythrough an attachment hole 611 formed in a side surface of the recess601. Further, an attachment hole 612 for screw fastening is formed in aright end of the second area 601 b in fixedly mounting the upper cabinet3 on the lower cabinet 2. Furthermore, a transversely extending grooveportion 613 is formed in the right end of the second area 601 b. Anopening 613 a is formed in a left end of the groove portion 613, and amicro switch (not shown) for detecting whether the lamp cover 11 iscompletely closed faces the groove portion 613 through the opening 613a.

FIGS. 16A and 16B are diagrams showing an arrangement of the prism cover10. FIG. 16A is a perspective view of the prism cover 10, when viewedfrom a front side of the prism cover 10, and FIG. 16B is a perspectiveview of the prism cover 10, when viewed from a back side of the prismcover 10.

The prism cover 10 is formed into a rectangular shape, and has athickness substantially equal to the depth of the recess 601. Aprojection 701 is formed at two positions on a left end of the prismcover 10. Further, an attachment piece 702 having an attachment hole 702a is provided substantially in the middle on a right end of the prismcover 10.

A metal shield plate 703 is mounted on a back surface of the prism cover10 to suppress unwanted radiation from e.g. the prism opening 602.Further, a transversely extending guided rib 704 is formed on each of afront end and a rear end of the prism cover 10.

FIGS. 17A and 17B are diagrams showing an arrangement of the lamp cover11. FIG. 17A is a perspective view of the lamp cover 11, when viewedfrom a front side of the lamp cover 11, and FIG. 17B is a perspectiveview of the lamp cover 11, when viewed from a back side of the lampcover 11.

The lamp cover 11 is constituted of an upper plate 801 and a side plate802. As shown in FIGS. 1A and 1B, the upper surface of the upper cabinet3 has a moderately curved shape such that the upper surface is loweredfrom a central part thereof in leftward and rightward directions. Theupper plate 801 is moderately inclined toward the side plate 802 inconformity with the upper surface shape of the upper cabinet 3.

A metal shield plate 803 is provided on a back surface of the upperplate 801. The shield plate 803 is mounted on a holding portion 804which is slightly bulged from the back surface of the upper plate 801.The shield plate 803 shields the lamp opening 606 in mounting the lampcover 11 on the upper cabinet 3. The shield plate 803 suppressesunwanted radiation from the lamp opening 606, and protects the lampcover 11 from a heat generated in the lamp unit 13 (light source lamp300). A projection 805 is formed at two positions on a left end of theholding portion 804.

Support ribs 806 are respectively formed on a front end and a rear endon the back surface of the upper plate 801. Because of the arrangementthat each of the support ribs 806 has such a shape that a certain partthereof is cut away between a left end and a right end thereof, and theupper plate 801 is inclined, the height of each of the support ribs 806is reduced toward the side plate 802. The support ribs 806 support theupper plate 801 with respect to the bottom surface of the recess 601 inmounting the lamp cover 11 on the upper cabinet 3 (see FIG. 18B).

Further, an arm portion 807 is formed on each of the front end and therear end of the back surface of the upper plate 801. Each of the armportions 807 has a lead end thereof bent toward the side plate 802, andthe outwardly extending stem portion 808 is formed at the lead end ofeach of the arm portions 807. Further, a stopper portion 809 extendingin parallel to the lead end is formed on each of the arm portions 807(see FIG. 20).

Further, a rib 810 to be housed in the groove portion 613 of the uppercabinet 3 is formed on the back surface of the upper plate 801. When thelamp cover 11 is completely closed, the micro switch is pressed by therib 810. Then, the micro switch is turned on, and it is detected thatthe lamp cover 11 is completely closed.

An attachment hole 811 is formed in the side plate 802.

Thus, when the prism cover 10 is mounted on the upper cabinet 3, theprism cover 10 is housed in the recess 601 from the right end of thefirst area 601 a, and slidingly moved in leftward direction. Then, asshown in FIG. 18A, the guided ribs 704 are housed in the clearancesbetween the guide ribs 603 and the bottom surface of the recess 601.This suppresses an upward movement of the prism cover 10.

When the prism cover 10 is completely closed, the projections 701 arereceived in the insertion holes 604 of the recess 601. This suppressesan upward movement of the left end of the prism cover 10. Further, theattachment hole 702 a of the prism cover 10 is aligned with the screwhole of the nut 605. Then, by screw-fastening the nut 605, the prismcover 10 is fixedly mounted on the upper cabinet 3.

Next, as shown in FIG. 18B, when the lamp cover 11 is mounted on theupper cabinet 2, the arm portions 807 are housed in the guide grooves609 from above, and the stem portions 808 are received in the guideholes 609 a. In the insertion operation, the stem portions 808 arereceived in the guide holes 609 a through the openings 609 b.Thereafter, the lamp cover 11 is slidingly moved in leftward direction.Then, the stem portions 808 are moved in leftward direction along theguide holes 609 a. As a result of the above operation, an upwardmovement of the lamp cover 11 is suppressed by the stem portions 808received in the guide holes 609 a and the support ribs 806.

When the lamp cover 11 is completely closed, the left end of the lampcover 11 is placed over the right end of the prism cover 10. As a resultof the above operation, the screws of the prism cover 10 are covered bythe lamp cover 11. Further, the projections 805 of the lamp cover 11 arereceived in the insertion holes 608 of the recess 601. As a result ofthe above operation, an upward movement of the left end of the lampcover 11 is suppressed. Further, the attachment hole 811 of the lampcover 11 is aligned with the screw hole of the nut 610. Then, byscrew-fastening the nut 610, the lamp cover 11 is fixedly mounted on theupper cabinet 3.

As described above, as shown in FIGS. 1A and 1B, by performing the aboveoperations, both of the prism cover 10 and the lamp cover 11 are mountedon the upper cabinet 3.

The lamp unit 13 (light source lamp 300) and the prism unit 16 aredeteriorated by a long-time operation. In such a case, it is necessaryto replace the lamp unit 13 and the prism unit 16 with new ones. Thelamp unit 13 is easily deteriorated, as compared with the prism unit 16,and the replacement frequency of the lamp unit 13 is larger than thereplacement frequency of the prism unit 16.

In the case where the lamp unit 13 is replaced, the lamp cover 11 isopened to mount or dismount the lamp unit 13 through the lamp opening606. Replacement of the lamp unit 13 may be performed by the user.

FIGS. 19A and 19B are diagrams showing a state that the lamp cover 11 isopened. FIG. 19A shows a state that the lamp cover 11 is halfway opened,and FIG. 19B shows a state that the lamp cover 11 is completely opened.FIG. 20 is a cross-sectional view showing essential parts of the uppercabinet 3 for describing an operation to be performed for the lamp cover11 in the case where the lamp cover 11 is opened.

In the case where the lamp unit 13 is replaced, the user unfastens thescrew, and slidingly moves the lamp cover 11 in rightward direction. Byperforming the above operation, as shown in FIG. 19A, the lamp opening606 is gradually opened. Then, as shown by the broken line in FIG. 20,the user is allowed to move the stem portions 808 in rightward directionwithin the guide holes 609 a.

When the stem portions 808 reach the right end of the guide holes 609 a,the lamp cover 11 is not slidingly moved any more. In this state, aright end portion of the lamp opening 606 is still covered by the lampcover 11.

Next, the user pushes a portion of the lamp cover 11 projecting from theright end of the upper cabinet 3 in downward direction. Then, as shownby the solid line in FIG. 20, the lamp cover 11 is pivotally moved aboutthe stem portions 808. In this state, as shown in FIG. 17B, since thesupport ribs 806 are cut away at a position around the arm portions 807,there is no likelihood that the support ribs 806 may be abutted againsta corner of the upper cabinet 3 in pivotally moving the lamp cover 11.

As described above, as shown in FIG. 19B, the lamp cover 11 standsupright along the right side surface of the upper cabinet 3, and thelamp opening 606 is completely opened. In this state, as shown in FIG.20, the stopper portions 809 are abutted against the right side surfaceof the upper cabinet 3.

As shown in FIG. 20, a bulging projection 609 c is formed below and at aright end of each of the guide holes 609 a. The height of the projection609 c is very small. Accordingly, by applying a small external force inslidingly moving the lamp cover 11, the stem portions 808 are moved overthe projections 609 c, and reach the right ends of the guide holes 609a, respectively. In this state, left portions of the stem portions 808are supported by the projections 609 a. Since the stem portions 808 areeasily rotatable, the lamp cover 11 is smoothly and pivotally moved.

When the lamp opening 606 is completely opened, the user is allowed todismount the deteriorated lamp unit 13 through the lamp opening 606.Then, the user is allowed to house a new lamp unit 13 in the lowercabinet 2 through the lamp opening 606. Then, the user is allowed toclose the lamp cover 11, and fasten the screw to fixedly mount the lampcover 11 on the upper cabinet 3 by a sequence opposite to the sequenceto be performed in opening the lamp opening 606.

In the case where the prism unit 16 is replaced, the prism opening 10 isopened, and the prism unit 16 is mounted or dismounted through the prismopening 602. Replacement of the prism unit 16 is performed by aserviceperson.

FIGS. 21A and 21B are diagrams showing a state that the prism cover 10is opened. FIG. 21A shows a state that the prism cover 10 is halfwayopened, and FIG. 21B shows a state that the prism cover 10 is completelyopened.

In the case where the prism unit 16 is replaced, a serviceperson opensthe lamp cover 11 by the above sequence. Then, the servicepersonunfastens the screw, and slidingly moves the prism cover 10 in rightwarddirection. Then, as shown in FIG. 21A, the prism cover 10 is slidinglyretracted in the space of the recess 601 which is defined by opening thelamp cover 11. Then, as shown in FIG. 21B, by slidingly moving the prismcover 10 to the right end of the recess 601, the prism opening 602 iscompletely opened.

When the prism opening 602 is completely opened, the serviceperson isallowed to dismount the deteriorated prism unit 16 through the prismopening 602. Then, the serviceperson is allowed to house a new prismunit 16 in the lower cabinet 2 through the prism opening 602. Then, theserviceperson is allowed to close the prism cover 10, and fasten thescrew to fixedly mount the prism cover 10 on the upper cabinet 3 by thesequence opposite to the sequence to be performed in opening the prismopening 602. Lastly, the lamp cover 11 is closed.

As described above, in this embodiment, by slidingly moving the prismcover 10, the prism opening 602 is opened. Further, by slidingly movingthe lamp cover 11, the lamp opening 606 is opened. In this way, even ifthe space defined above the cabinet 1 is small in installing theprojector, the prism opening 602 and the lamp opening 606 can besufficiently opened.

Further, in this embodiment, since both ends of each of the prism cover10 and the lamp cover 11 are securely fixed so that the both ends arenot moved in upward direction in slidingly moving the prism cover 10 andthe lamp cover 11, there is no or less step difference between the prismcover 10 and the lamp cover 11, and the upper cabinet 3. Thus, asophisticated appearance of the projector is secured.

Further, the embodiment is configured to slidingly move the prism cover10 with respect to the second area 601 b in opening the prism cover 10.Accordingly, there is no need of additionally forming a recess in theupper cabinet 3 to house the slidable prism cover 10. This isadvantageous in simplifying the arrangement of the upper cabinet 3.

In the above case, it is necessary to open the lamp cover 11 to open theprism cover 10. However, since the replacement frequency of the prismunit 16 is smaller than the replacement frequency of the lamp unit 13, aburden of operation is reduced.

Further, in this embodiment, when the lamp cover 11 is slidingly movedto some extent, the lamp cover 11 is bent downward, thereby completelyopening the lamp opening 606. This enables to reduce the sliding amountof the lamp cover 11, and suppress a projecting amount of the lamp cover11 from the cabinet 1 in slidingly moving the lamp cover 11. Thus, it ispossible to reduce the space for sliding movement, which is necessary inopening or closing the lamp cover 11. Further, even if an external forceis applied from above by e.g. hitting of a user's/serviceperson's handin a state that the lamp cover 11 is opened to the right end, the forceis absorbed by pivotal movement of the lamp cover 11. Thus, it ispossible to prevent damage or breakage of the lamp cover 11.

In this embodiment, the prism unit 16 is disposed in the central part ofthe cabinet 1, and the lamp unit 13 is disposed near the right sidesurface of the cabinet 1. Alternatively, the prism unit 16 may bedisposed at a position near the side surface of the cabinet 1, dependingon the structure of the projector. In the modification, the arrangementsof the prism cover 10 and the lamp cover 11 are opposite to those in theembodiment. In the modification, since it is necessary to open the prismcover in order to open the lamp cover, a burden of operation may beslightly increased.

Further, it is not necessary to dispose the prism opening 602 and thelamp opening 606 independently of each other. Alternatively, the prismopening 602 and the lamp opening 606 may be communicated with eachother. Specifically, a single opening for covering the disposition areasof the lamp unit 13 and the prism unit 16 may be formed in the cabinet 1so that the lamp unit 13 and the prism unit 16 can be dismounted throughthe single opening. In the modification, the prism cover 10 and the lampcover 11 may be formed into one cover.

The embodiment of the invention has been described as above, but theinvention is not limited to the foregoing embodiment. Further, theembodiment of the invention may be changed or modified in various waysas necessary, as far as such changes and modifications do not departfrom the scope of the claims of the invention hereinafter defined.

1. A projection display device comprising: a light source including alight emitting portion, a reflector which reflects light emitted fromthe light emitting portion, and a fixing portion which fixedly mountsthe light emitting portion with respect to the reflector; a first airsupply portion and a second air supply portion which supply a coolingair; a first air drawing portion which separates the cooling air fromthe first air supply portion into streams of the cooling air to guideone of the streams of the cooling air into an interior of the reflectorin a first direction and to guide the other of the streams of thecooling air to the fixing portion in a second direction; and a secondair drawing portion which separates the cooling air from the second airsupply portion into streams of the cooling air to guide one of thestreams of the cooling air into the interior of the reflector in a thirddirection and to guide the other of the streams of the cooling air tothe fixing portion in a fourth direction.
 2. The projection displaydevice according to claim 1, wherein the third direction is a directionopposite to the first direction, and the fourth direction is a directionopposite to the second direction.
 3. The projection display deviceaccording to claim 1, wherein the first air drawing portion and thesecond air drawing portion directly blow the other stream of the coolingair to the fixing portion.
 4. The projection display device according toclaim 2, wherein the first air drawing portion and the second airdrawing portion directly blow the other stream of the cooling air to thefixing portion.
 5. A projection display device comprising: a lightsource including a light emitting portion, a reflector which reflectslight emitted from the light emitting portion, and a fixing portionwhich fixedly mounts the light emitting portion with respect to thereflector; a first air supply portion and a second air supply portionwhich supply a cooling air; a first air drawing portion which separatesthe cooling air from the first air supply portion into two separatestreams of the cooling air to guide one of the streams of the coolingair into an interior of the reflector in a first direction and to guidethe other of the streams of the cooling air to the fixing portion,outside of the reflector, in a second direction; and a second airdrawing portion which separates the cooling air from the second airsupply portion into two separate streams of the cooling air to guide oneof the streams of the cooling air into the interior of the reflector ina third direction and to guide the other of the streams of the coolingair to the fixing portion, outside of the reflector, in a fourthdirection.